Alternative therapies a mother wishes to explore to prevent her seven-year-old from having radiotherapy to treat a brain tumour, were "not an option", the high court has heard.

Sally Roberts, 37, was refused extra time to seek experts in alternative treatments including immunotherapy, boron neutron capture therapy, photo-dynamic therapy and hyperbaric oxygen therapy for her son Neon, who is receiving treatment for medulloblastoma.

Refusing her application to adjourn the case until the new year, judge Mr Justice Bodey said any further delays would be detrimental and not in Neon's "best interests". Roberts, had wanted to call evidence from alternative and integrated medical practitioners about the treatments, which also included Tyrosine-Kinase inhibitors and molecular targeting therapy.

But counsel for the hospital trust treating him, which cannot be named, said Neon should not be subjected to "experimental therapies" and "unproven treatments". The judge is expected to rule on Friday if Neon must undergo radiotherapy.

Neon underwent an emergency operation on Wednesday after the judge ordered the surgery against the mother's wishes. Roberts asked for a delay, saying she was "not persuaded of the need and not persuaded of the urgency" of surgery, and wanted a second opinion to investigate whether the growth was residual or regrowth tumour from a previous operation in October, or if it could be "inflamed scar tissue".

Bodey ordered surgery, after medical practitioners treating Neon said it was "highly, highly, likely he would die over a relatively short period of time".

Even at the eleventh hour Roberts tried to prevent it, applying to the court of appeal in the early hours of Wednesday morning, just hours before he was due to be operated on. Her appeal failed.

The judge heard that surgeons had "found evidence of a tumour nodule" which a biopsy showed was "consistent with medulloblastoma". After the second operation surgeons now felt no obvious tumour had been left behind, but that adjuvant therapies such as radiotherapy and chemotherapy were required "because of the risk of microscopic tumour being left behind". He was now "standard" rather than "high risk", which was "very, good news".

Roberts made headlines when she went missing with Neon for four days earlier this month to prevent him having radiotherapy following his first operation.

The court heard doctors want to start radiotherapy no later than 16 January, and ideally by 9 January. Roberts has prevented her son from taking antiemetic drugs, which control nausea, after the operation, the court heard.

Ian Peddie, QC, representing Roberts, whose case is being funded by legal aid, said: "The mother remains concerned that radiotherapy is not in [Neon's] best interests." She required time to find doctors who could offer alternative "credible medical treatment to the therapy proposed".

But, opposing any further delays, Victoria Butler-Cole, representing the hospital trust, said it was clear that at least one on the list of four private practitioners provided by Roberts, "was not familiar or remotely expert" in the treatment of medulloblastoma. The diseasemedulloblastoma, she said, "is spelled wrongly" and his description of it seemed to have been from the internet or newspaper cuttings.

Another was "not GMC-registered". None of them was "on the specialist [GMC] register", meaning it was highly unlikely they were specialists in paediatric oncology. The website of the doctors described using "herbs, nutritional supplements, enzymes, diet and psychological healing strategies in treatment for cancer", added Butler-Cole. She compared this with treatment at "a hospital and centre of excellence that offered the gold standard treatment being offered to all other children in this country who have this disease".

The prospect was that Neon would not be admitted to any "formal proper research programme" but rather to "unproven treatments".

It was unlikely any such alternatives would be funded on the NHS. Butler-Cole said: "The dose of realism that is required is whatever these doctors may be prepared to say or prepared to do, provided funding could be found from a private source, the prospect of the court accepting their views in preference to the gold standard in this country is so small as to enable the court to take a robust approach to the mother's position today."

Neon's father, Ben, 34, an IT consultant from west London, who is estranged from Roberts, was "anxious" that an order on the radiotherapy be made this week. He had supported the second surgery, and was at his son's hospital bedside on Thursday. A leading paediatric oncologist, treating Neon, known only as Dr A said none of Roberts' proposed therapies "are alternatives to standard treatment" for medulloblastoma.

Cross-examined by Peddie, he said the chance of a someone undergoing radiotherapy of having another benign or malignant tumour in the future was between 2% and 4%. He said any decline in a seven-year-old's IQ as a result of radiotherapy was "very marginal", just 0.42 points per year over four years, using a standard 100-point IQ.There was an 86% five-year survival rate for medulloblastoma for those undergoing radiotherapy treatments. Of the effects on Neon, he said: "I can't guarantee that somebody would be exactly the same as if they didn't have a medulloblastoma tumour. But this is a medulloblastoma that we can cure." But Roberts told the judge: "I still feel the same, that there are other ways." She had spent "many, many hours of research and study", she said, and had been "inundated" with emails about other treatments due to the publicity of her case. Regarding proposed applications that Neon would live with his father during treatment, Roberts, a mother-of-two originally from New Zealand, said she agreed "as long as I can see my son every day and be part of his recovery".

Asked about Neon's passport, and fears she might return to New Zealand, she said her son had no current passport. "I would never take him away from his father," she said. "I had my children with an Englishman and I can't take them away from their father." The case continues.

• The above article was amended on 21 December 2012. An editing error led to us calling antiemetic drugs anti-hermetic drugs. This has been corrected.